linux-kernel - Re: [PATCH v2] dmaengine: at_xdmac: Fix wrongfull report of a channel as in use

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Message-ID: <42d281c0-e44e-0b59-825d-3fcca8f523d5@microchip.com>
Date:   Wed, 23 Jan 2019 16:41:05 +0000
From:   <Codrin.Ciubotariu@...rochip.com>
To:     <Ludovic.Desroches@...rochip.com>, <vkoul@...nel.org>
CC:     <dmaengine@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] dmaengine: at_xdmac: Fix wrongfull report of a channel
 as in use

On 23.01.2019 18:33, Codrin Ciubotariu - M19940 wrote:
> From: Codrin Ciubotariu <codrin.ciubotariu@...rochip.com>
> 
> atchan->status variable is used to store two different information:
>   - pass channel interrupts status from interrupt handler to tasklet;
>   - channel information like whether it is cyclic or paused;
> 
> This causes a bug when device_terminate_all() is called,
> (AT_XDMAC_CHAN_IS_CYCLIC cleared on atchan->status) and then a late End
> of Block interrupt arrives (AT_XDMAC_CIS_BIS), which sets bit 0 of
> atchan->status. Bit 0 is also used for AT_XDMAC_CHAN_IS_CYCLIC, so when
> a new descriptor for a cyclic transfer is created, the driver reports
> the channel as in use:
> 
> if (test_and_set_bit(AT_XDMAC_CHAN_IS_CYCLIC, &atchan->status)) {
> 	dev_err(chan2dev(chan), "channel currently used\n");
> 	return NULL;
> }
> 
> This patch fixes the bug by adding a different struct member to keep
> the interrupts status separated from the channel status bits.
> 
> Fixes: e1f7c9eee707 ("dmaengine: at_xdmac: creation of the atmel eXtended DMA Controller driver")
> Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@...rochip.com>
> Acked-by: Ludovic Desroches <ludovic.desroches@...rochip.com>
> ---

Forgot to add:

Changes in v2:
  - changed commit message;

If you need v3 for this let me know.

Best regards,
Codrin